Imine-based highly polar achiral unsymmetrical four-ring bent shaped liquid crystals: Design, synthesis and characterization

Herein, we have designed and synthesized a new homologous series of polar achiral bent-shaped compounds incorporating two imines and one ester linkage in the molecular framework. It has been observed that a stable and significantly longer range of nematic phase was achieved for compound A5. The homologue A6 exhibited only nematic cybotactic and smectic A mesophase. The intermediate homologue A7 and A8 displayed nematic cybotactic as well as smectic A and an unknown smectic X phase. Compounds A10 to A14, bearing the longer alkyl chains, showed the ordered smectic A and smectic X phase. In the case of smectic A and smectic X phase limits, the number of correlated units (xi/d(SAXS)) was found to be around 20, while in the case of nematics, it ranged from 1-3. However, this value has been recorded up to nine correlated units in the case of cybotactic nematic ordering. All of these materials have a significantly high dipole moment of around similar to 10 Debye computed via Density Functional Theory calculations, which is essential for high dielectric materials and furthermore can stabilize the highly anticipated ferroelectric nematic phase. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, a new series of nonchiral bent-shaped compounds incorporating two imines and one ester linkage in the molecular framework were designed and synthesized. It was found that certain compounds exhibited a stable and significantly longer range of nematic phase, while others showed different anisotropic phases.